INFLUENCE OF RESTRICTED FEMALE-LAMB CONTACT IN LENGTH OF POSTPARTUM ANESTROUS IN PELIBUEY SHEEP

Abstract

The study was carried out to evaluate the effect of restricting the ewe-lamb contact on the length of postpartum anestrous. We used 28 adult Pelibuey sheep and their young. One day after birth, females were randomly assigned to one of two testing groups. Restricted Suckling (RS, n = 17 sheep, n = 21 lambs), separation of ewes from lambs for 7 h/d (8:00 to 15:00 h). Unrestricted Suckling (US, n = 11 sheep, n = 13 lambs), with interaction between the ewes and lambs 24 h/d. Blood samples were collected from sheep, birth to 105 d postpartum and progesterone concentrations determined by radioimmunoassay. The ewes and lambs were weighed every 15 d and mortality was recorded during the experiment. The intervals between calving to first ovulation in females, were analyzed using an ANOVA, the weaning weight and daily gain in lambs were evaluated with an analysis of covariance, and weight changes in females with multivariate analysis for repeated measurements over a determined period of time. The proportion of females ovulating at 105 d postpartum and lamb mortality were evaluated using x2 test. The postpartum anestrous in RS (83.2 + 5.5 d) was higher (P<0.05) than in US (58.8 + 5.5 d), 100% of US females ovulated within 105 d postpartum, in contrast (P<0.05), only 64.7% in RS ovulated in the same period. US lambs gained more weight (172 + 0.6 g/d, P <0.05) and had a higher weaning weight (13.2 + 0.5 kg, P<0.05) compared with RS (143 + 0.6 g / d and 11.4 ± 0.4 kg, respectively). The mortality in lambs was similar (P> 0.05) between groups. The restriction of the ewe-lamb contact for 7 h/d in Pelibuey prolongs the duration of postpartum anestrous, and in the offspring, it reduced the weaning weight and daily weight gain, without affecting mortality. We suggest that this type of management causes psychosocial stress in sheep and possibly inhibits the secretion of LH and delays postpartum ovulation.